Sterilization method and apparatus

• US 5,547,635 A
• Filed: 11/10/1993
• Issued: 08/20/1996
• Est. Priority Date: 10/22/1987
• Status: Expired due to Fees

• Current Assignee: Robert E. Duthie Jr
• Original Assignee: Robert E. Duthie Jr
• Inventors: Duthie, Robert E. Jr.
• Primary Examiner(s): Warden, Robert J.
• Assistant Examiner(s): JASTRZAB, KRISANNE MARIE
• Application Number:
  US08/150,280
• Time in Patent Office: 1,014 Days
• Field of Search: 422/22, 422/24, 422/121, 422/186.05, 422/186.3, 250/493, 250/455.11
• US Class Current: 422/24
• CPC Class Codes: A61L 2/10 Ultraviolet radiation

Abstract

A sterilization method and apparatus wherein microorganisms are exposed to ultraviolet light characterized by providing and operating a mercury/gallium metal halide ultraviolet light source in a manner exposing the microorganisms to ultraviolet light and a gaseous titanium dioxide emitted from the source for an exposure time in the range from about 0.3 seconds to about 60 seconds and at an exposure distance in the range from about 0.25 inch to about 4.0 inches, the ultraviolet light being emitted through a wavelength range from about 175 nanometers to about 450 nanometers with the relative energy being in the range from equal to or greater than 1.3 to equal to or less than 250 microwatts/sq.cm./nanometer at one meter. When the microorganisms are on the surface of an object, the surface is exposed to the ultraviolet light and to the titanium dioxide to provide a dynamic sterilization process on the surface so that the critical surface tension on the surface is changed and biological contaminant layers are actively removed from the surface without altering the originality of the surface which eliminates any shielding or screening of microorganisms on the surface and which provides complete sterilization on the surface with microcombustion of microorganisms. In addition, ozone-free quartz is provided in operative relation between the light source and the microorganisms.

Claims

1. In a method of sterilizing a surface of an object wherein the nature of the surface is such that the critical surface tension is changeable and the physical and chemical originality of the surface is unalterable when exposed to high energy ultraviolet light and a metal oxide and wherein there is provided a mercury/gallium metal halide ultraviolet light source having an ozone-free metallic doped quartz envelope, the improvement comprising:

a) placing the object with the surface to be sterilized in proximity to said light source at a distance providing rapid heat transfer between said light source and said object and surface;

b) operating said light source to emit high energy ultraviolet light and a metal oxide, said ultraviolet light being emitted through a wavelength range from about 175 nanometers to about 450 nanometers;

c) exposing said surface to said ultraviolet light and to said metal oxide for a time sufficient to provide a dynamic sterilization process including irradiation by said ultraviolet light, sputtering by said metal oxide and said rapid heat transfer simultaneously on said surface so that the critical surface tension on said surface is changed and biological contaminant layers are actively removed from said surface without altering the originality of said surface which eliminates any shielding or screening of microorganisms on said surface and which provides complete sterilization on said surface with microcombusting of microorganisms; and

d) wherein the portion of the energy of said ultraviolet light in the wavelength range from about 350 nanometers to about 450 nanometers provides said sputtering and the portion of the energy of said ultraviolet light in the wavelength range from about 175 nanometers to about 300 nanometers provides sterilization at about 253.7 nanometers.

2. A method according to claim 1, wherein said metal oxide is titanium oxide.

3. A method according to claim 1, wherein the range of relative energy of said ultraviolet light is between equal to or greater than 1.3 and equal to or less than 250 microwatts/sq. cm./nanometer at one meter.

4. A method according to claim 1 wherein the exposure time of said surface is in the range from about 0.3 seconds to about 60 seconds.

5. A method according to claim 1, wherein the distance between said light source and said surface is in the range from about 0.25 inch to about 4.0 inches.

6. A method according to claim 1, wherein said step of exposing said surface is carried out in a standard atmosphere.

7. A method according to claim 1, wherein said steps of exposing said surface is carried out in an enclosure under standard atmospheric conditions.

8. In a sterilization method wherein microorganisms are exposed to ultraviolet light and wherein there is provided an ultraviolet light source comprising a mercury/gallium metal halide lamp having an ozone-free metallic doped quartz envelope, the improvement comprising:

a) operating said lamp to expose microorganisms to ultraviolet light and titanium dioxide emitted from said lamp for an exposure time in the range from about 0.3 seconds to about 60 seconds and at an exposure distance in the range from about 0.25 inch to about 4.0 inches to provide rapid heat transfer between said light source and said microorganisms, the ultraviolet light being emitted through a wavelength range from about 175 nanometers to about 450 nanometers with the relative energy being in the range between equal to or greater than 1.3 and equal to or less than 250 microwatts/sq. cm./nanometers at one meter to provide dynamic sterilization including the simultaneous process of irradiation by said ultraviolet light, sputtering by said metal oxide and said rapid heat transfer; and

b) wherein the portion of the energy of said ultraviolet light in the wavelength range from about 350 nanometers to about 450 nanometers provides said sputtering and the portion of the energy of said ultraviolet light in the wavelength range from about 175 nanometers to about 300 nanometers provides sterilization at about 253.7 nanometers.

9. The improvement according to claim 8, wherein said microorganisms are exposed to said ultraviolet light and titanium dioxide under standard atmospheric conditions.